With rising fuel costs, there are increasing demands being placed upon aircraft to be more fuel efficient, that is, to go at least as far or further while consuming the same amount or less fuel. By becoming more fuel efficient, the costs associated with the fuel consumption of a fleet of aircraft would be reduced, and the impact upon the environment would be correspondingly decreased. Additionally, a more fuel efficient aircraft carrying the same amount of fuel could carry a greater payload and/or have a greater mission range or time. In order to construct aircraft having improved fuel efficiency, a variety of techniques to reduce the drag and therefore increase the fuel efficiency of an aircraft have been studied and, in some instances, implemented.
Another technique considered in regard to increasing the fuel efficiency of aircraft and reducing the dependence of an aircraft upon fossil fuels has relied upon the harvesting of solar energy and the utilization of solar energy to at least partially power aircraft. In this regard, the incorporation of solar cells upon the exterior surfaces of aircraft has been considered. However, the solar cells generally disadvantageously increase the weight and the drag of the aircraft and correspondingly reduce the fuel efficiency of the aircraft, notwithstanding the gains attributable to the harvesting of solar energy by the solar cells. Additionally, the relatively low energy conversion efficiency and the relatively high surface area to power output ratio of solar cells has also limited their utilization as an alternative energy source for aircraft.
As such, it would be desirable to develop more fuel efficient aircraft which rely, at least to some degree, upon the collection of solar energy, thereby potentially decreasing operational costs and the impact upon the environment.